Landing gear control and indicating arrangement



y 1947. H. G. coNwAY 2,420,066

LANDING GEAR CONTROL AND INDICATING ARRANGEMENT Filed Oct. 9, 1942 I I 15 15 d2 21 km x 154;

Patented May 6, 1947 LANDING GEAR oo'NTitoL ANn iNnicA'rINo ARRANGEMENT Hugh Graham Conway, Warrington; England. assignor to Aeronautical & Mechanical InvestmentsLimited, a British company Application October 9, 1942, Serial No. 461.489 In Great Britain August 22,1941

2 Claims. ire-s11) This invention comprises improvements in or relating to control devices for the movement of aircraft-11ndercarriages and: other parts. It is an object of the invention to facilitate control of the movementsof aircraft parts by pilots and other persons in charge, particularly of undercarriages, although the invention could be applied to the control of the movements of parts such as bomb doors or releases or any occasionally movable parts if desired.

The invention comprises, in control devices for the movement of aircraft-'undercarriages and other occasionally movable aircraft parts, the provision of means whereby themovemen't of the part to be controlled is determined by an-ele'ctric out invention. The, means" for determining the push-button or like manual control-switch looperation of the jack [4 comprises a push-button cated close to the pilot and the push buttons or [5 which when operated will close an. electric the like are illuminated by electric lamps or other circuit, causing retraction of the jack l4 and raisindicators-within or beside them; which indicators ing of the undercarriage, and another push butare in circuit with switch-means so operatively 24; ton [6 which when operated will cause extension connected to the parts thus moved that their of the jack l4 and lowering, of the undercarriage. operation constitutes an indication of the correct The connections from the push-buttons l5, IE to operation of the parts; the valves for controlling the hydraulic circuit of Morespecifically, as-applied to aircraft-underthe jack M are not shown in the drawing. carriage control devices; the invention comprises 5 In addition to the push-buttons l5,- IG there: is the-employment of an electric control device comprovided an indicator-lamp ll. The push-buttons prising a down push-button or like switch for l5, [6 are made hollow and transparent and each down movement. an up push-button or like comprise fittings for the supply of electric curswitch for up movement, means to cause the unrent and an internal illuminating lamp bulb or dercarriage to move down when the down bulbs. In the diagram, Figure 1, the lamp bulb switch is operated and up when the up switch of the up buttons I5 is' indicated separately below is operated,- an electric lamp or other electric the push buttons' at 18, the bulb of the push indicator associated with each such switch and button It is shown at I!) and the bulb of the iniurther switch-means associated with the underdicator window I! is shown at 2fl; carriage and so connected to the indicators of the 55 As will be seen the push-buttons l 5, l6 and the up and down switchesthat on upward moveindicator window I! are arranged in a switch mentof the undercarriage the up switch indiblock-"2| so that they project from the face of c'ator' operates and on downward movement of the switch block and the push-buttons l5, l8 are the undercarriage the down switch indicator made large enough to be readily operated by the operates. gloved hand of an aircraft pilot. Conveniently,- It is a feature of the invention that the pushthe up button is labelled Up and is coloured button or like switchesneed be operated only amber, the down button is labelled Down momentarily, but the indicators are maintained and coloured red and the indicator lamp I7 is in operation, once movement of the part oomcoloured green. mences, independently of release of the switches. The movable cylinder H of the shock absorber By the present invention the pilot or other op'-' leg of the undercarriage is pivoted at 22 to a orator gets an indication when he presses the sliding. rod 23 on which is mounted an insulating button of whether the devices are responding to "block 24 capable of a limited degree of movement his control and he does not have to move his eyes from side to side between stops 25, 26. The block from the button which he is pressing in order to 24 is friction tight on the sliding rod 23 and this observe the indication of the response. mechanism constitutes a friction-drive lost- The following is a description by way of exmotion connection, so that the greater part of ample of an installation in accordance with the the movement of the jack H is lost but initialinvention as applied to. the operation of a re movement in either direction moves the friction tractable: undercarriage. strut: blocked against the stop 25 or 26- as the 'caSeT' 2 In the accompanyingv drawings: I Figure 1'. is a diagram of electrical connections; Figure 2 is apart section of a push-button, for

use in accordance with theinvention, on the line 2-2 of Figure 3;.

Figure 3 is a centrallongitudinal section upon theline 3-3 of Figure 2, and V Figure 4. is a cross-section: on the line 4--4 of Figure 2.

Referring to Figure 1-, the undercarriage comprises a leg ll pivoted at l2 and provided with a landing wheel l3 and retraction'jack [4. These parts may be of any desired or usual construction and, in themselvesgc'onstitute no part of the presmay be; thus when the undercarriage is being raised the friction block 24 will move in one direction and when the undercarriage is being lowered it will move in the other direction. The friction block 24 is located between two arms 21, 28 of a two-way switch operating between contacts 29, 39. The contact 29 which is closed when the undercarriag rises is connected by a line 3| to the lamp IS in the up push-button l and the contact 36 which is closed when the undercarriage moves downward is connected by a line 32 to the lamp I9 in the down push-button IS. The other terminals of the lamps |8, |9 are connected together at 33 and thence by a line 34, normally closed switch contacts 35, 36, further normally closed switch contacts 31, 38 and line 46 to one terminal of a battery 4| or other source of electric supply. The other terminal of the battery 4| is connected by a line 42 to the switch arms 21, 28.

A projection 43 from the hub of the undercarriage shock absorber serves to engage in either of its extreme positions insulated blocks 44, 45 on the before-mentioned switch members 35, 38 respectively. Thus when the undercarriage is fully lowered the contacts 31, 38 are opened and when it is fully raised the contacts 35, 36 are open, in either event breaking the circuit of the lamps |8, !9 so that whichever of them may have been illuminated (depending upon the direction of movement) is put out when the movement is completed; in this way the lamp |8 or l6, as the case may be, will only be illuminated when the undercarriage is actually moving.

The indicator lamp 20 before the green window I1 is connected by a line 46 to the battery 4| and by a line 4! to a contact arm 48 which engages a second contact arm 49 adjacent to the contact arm 38, before referred to, and like that arm connected to the battery 4| by the line 49. An insulating block 51] joins the arms 33, 49 so that when the downward movement of the undercarriage is completed the projection 43 on the hub of the shock absorber will not only break the circuit of the push-button lamps l8, IE! but will simultaneously make the circuit of the green lamp 20.

The operation will be obvious: If the pilot wishes to retract the undercarriage he presses momentarily upon the amber up push-button I5 and thereby starts retraction of the jack M. This continues and from the moment of its commencement the friction block 24 is moved toward the stop 25, engages the switch arm 2! and thereby closes the lamp-circuit of the push-button |5 on which the pilot has pressed. The push-button therefore, if the undercarriage responds to the impulse transmitted by the pilot, will light up. If it remains without moving, the pilot is aware of the fact because the push-button fails to light. When retraction is completed the push-button is automatically put out and thus the pilot is made immediately aware of completion of the movement. On the other hand, if the down pushbutton i6 is pressed the jack i4 begins to extend, the friction block 24 of the lost-motion connection is moved into contact with the switch contact arm 28, the lamp ii] in the down push-button is illuminated and the illumination continues, whether th pressure of the pilots hand is maintained or not, until the undercarriage is fully extended, whereupon the projection 43 will break the contacts 37, 38 and the down lamp will be extinguished. Not only will it be extinguished but at the same moment the contacts 48, 49 will be closed and the lamp 20 behind the green window will be illuminated, thus giving the pilot a positive indication that the undercarriage is fully extended and that landing is safe. Without the lamp H the pilot might consider it safe to land merely because the lamp I9 is extinguished and this would not allow for the possibility of error due to failure of current.

It will be clear that other apparatus, the operation of which is invisible to the operator, can have its movements signalled to the person controlling them in a similar way.

The internal construction of the switch block 2| is shown in Figures 2 to 4. It will be noted that the switch block comprises not only the body portion 2| but a removable base 5|, and cover 52. Translucent front portions of the push-buttons |5, |6 are screwed to body portions 53, 54, in which are located the lamps |8, |9. The body portions are made to slide through the switch block 2| and the cover 52, which are formed so as to afford guidance to keep them in a straight line. The push-buttons are interconnected by a lever 55 pivoted at 56 in the sides of the switch block 2| by means of hollow pivot screws 51. The lever has forked ends 58, 59 which engage pins projecting from the sides of the push-button body portions 53, 54. As can be seen from Figure 2, the lever is itself branched so as to engage both sides of each push-button. A spring 60 connects a pivot point 6| of the lower lever with the bottom 5| of the switch block. If this spring is a compression spring it will act as a toggle and will hold the push-buttons firmly over in either extreme position; if it is a tension spring it will tend to draw the push-buttons into the intermediate position, when the circuit of neither of them is closed, but the circuit of either button can be closed momentarily by pushing it inward and then releasing it.

The electric lamps |8, H) are connected to their circuits through terminals in the side of the switch block which are shown at 62 for the lamp l8 and 63 for the lamp l9. As seen in Figure 4 the terminals 62, 63 enter into the side of the switch block and support spring-rubbing members 64 which rub on the sides of the pushbutton bodies 53, 54. On these parts of the pushbutton bodies there are contacts 65 which are bent round beneath the body of the push-button and engage the terminals on 69 beneath them and at their free ends they carry contacts 10 which are adapted, when the push button is pushed inwardly, to close circuits 1| on other terminals 12. Thus when either of the push buttons |5 or H; are pressed inwardly it closes the circuit connecting the corresponding terminals 68, '12, but as soon as the push button moves out again the circuit is opened. If the push button is required to close simultaneously more than one circuit it is perfectly possible to locate two contact springs 61 side by side beneath a single push button.

It will be observed that the lamp 26 is mounted in a lamp holder 13 which is similar to the body portions 53, 54 of the push buttons |5, |6 except that it has a flange I4 which prevents inward sliding movement. This lamp holder is connected electrically to terminals 15 in the side of the switch block 2| in a way similar to that in which the lamps in the push buttons I5, [6 are connected to the terminals 62, 63.

Thus it will be appreciated that the terminals 62, 63, 15 are connected to the circuits shown in Figure 1, while the terminals 68, 12 are connected to the circuit which controls the movements of the undercarriage.

I claim:

1. In control devices for occasionally movable parts of aircraft or the like, in combination, a control element for causing movement of an aircraft part in one direction, a second control element for causing movement of said part in the opposite direction, power-operated means under the control of said elements for effecting the movements in both said directions, a first electric indicator disposed in proximity to the first named control element, a second electric indicator disposed in proximity to said second control element, indicator-actuating switch-means electrically connected with the indicators, and mechanical connections between the aircraft part itself and said switch-means, said switch-means and mechanical connections including a switch for energizing said first named indicator upon the initiation of movement of said part in the first named direction, a switch for energizing said second indicator upon initiation of movement of said part in said opposite direction, and limit switches engageable by said part at the ends of the movements thereof in both directions, means connecting each said limit switch in the circuit of the indicator which is energized by movement of the part toward the limit switch, so as to cut out said indicatorwhen said movement is completed.

2. In control devices for occasionally movable parts of aircraft or the like, in combination, a control element for causing movement of an aircraft part in one direction, a second control element for causing movement of said part in the opposite direction, power-operated means under the control of said elements for effecting the movements in both said directions, a first electric indicator disposed in proximity to the first named control element, a second electric indicator disposed in proximity to said second control element, indicator-actuating, switch-means electrically connected with the indicators, and mechanical connections between the aircraft part itself and said switch-means, said switch-means and mechanical connections including a switch for energizing said first named indicator upon the initiation of movement of said part in the first named direction, a switch for energizing said second indicator upon initiation of movement of said part in said opposite direction, limit switches engageable by said part at the ends of the movement thereof in both directions, and means connecting said limit switches in series and in circuit with both said indicators, so as to cut out the energized indicator when said movement is completed.

HUGH GRAHAM CONWAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,156,012 Doyle Apr. 25, 1939 506,729 Rex Oct. 17, 1893 1,715,505 Klumpp June 4, 1929 1,996,268 Ambuhl et a1 Apr. 2, 1935 1,719,471 Hoffman July 2, 1929 1,509,010 Wenzel Sept. 16, 1924 1,408,611 Larner Mar. 7, 1922 790,548 Atwood May 23, 1905 2,134,695 Bigman Nov. 1, 1938 2,185,748 Kebelman Jan. 2, 1940 1,118,827 Thomas Nov. 24, 1914 1,194,386 Horton Aug. 15, 1916 2,217,526 Pelikan Oct. 8, 1940 534,597 Atwood et al Feb. 19, 1895 1,176,202 Cheney Mar. 211, 1916 1,352,946 Felton Sept. 14, 1920 2,116,960 Brown et a1 May 10, 1938 2,407,018 MacKenzie Sept. 3, 1946 

